What was found
(CAN) DURING ENGINE GROUND RUN TO TROUBLESHOOT A PROPELLER SYNCHROPHASER DEFECT, THE NR 3 THROTTLE JAMMED AS IT WAS BEING RETARDED BELOW CROSSOVER. THE ENGINE WAS SUBSEQUENTLY SHUT DOWN USING THE EMERGENCY HANDLE. MAINTENANCE INVESTIGATION DETERMINED THE CAUSE TO BE A FAILED BEARING IN THE NR 3 ENGINE LOWER THROTTLE CONTROL PULLEY ASSEMBLY, RESULTING IN A MISALIGNED THROTTLE CABLE MECHANISM. THE THROTTLE JAM WAS CAUSED BY THE FAILED BEARING NO LONGER SUPPORTING THE ENGINE CONTROL ASSEMBLY IN THE CORRECT ALIGNMENT. THE BEARING WAS REPLACED AND THE AIRCRAFT RETURNED TO SERVICE.